Identification of a new amino acid mutation in the HN protein of NDV involved in pathogenicity

Abstract

The fusion (F) and haemagglutinin-neuraminidase (HN) proteins of Newcastle disease virus (NDV) are viral entry proteins and are recognized as the major virulence determinants. Previously, a lentogenic NDV virus (CE16) was derived from a mesogenic strain (CI10) through sequential passages in chick embryos. Whole-genome sequence analysis revealed that the two homologous strains shared the same F protein but differed in HN with two amino acid (aa) substitutions (A215G and T430A). To elucidate the molecular reasons for virulence attenuation, two original plasmids (HN-CI10 and HN-CE16) and two single-point mutants (G215A and A430T) reverse-mutated from HN-CE16 were constructed to analyse the known biological functions of HN. The results showed that the A430T substitution significantly weakened the haemadsorption (HAd) activity, increased the neuraminidase (NA) activity, improved the fusion-promoting activity, and enhanced the cleavage-promoting activity of HN-CE16. However, G215A failed to induce obvious functional changes. Therefore, the aa residue HN430 may play a key role in determining virulence. To test this hypothesis, further studies on A430T were conducted through reverse genetics using an infectious cDNA clone. At the viral level, the A430T-mutated virus showed dramatic promotion of viral plaque formation, propagation, and pathogenicity in vitro and in vivo. This study demonstrates a new virulence site associated with HN protein functions, viral propagation, and pathogenicity. All these findings could lay a foundation for illuminating the molecular mechanism of NDV virulence.

First Isolation and Characteristics of Bovine Parainfluenza Virus Type 3 from Yaks

“…Studies on other paramyxoviruses have proved that single aa mutations on HN, P, and L proteins have important biological significance. For instance: Studies on the Newcastle disease virus in the family Paramyxoviridae have shown that a single aa mutation in HN significantly altered the viral pathogenicity [35]; studies on the human parainfluenza virus type 3 have shown that a single aa mutation in L can regulate the levels of virus gene expression [36]. Therefore, the specific effects of the aa mutations in HN, P, and L proteins on the biological characteristics of the yak BPIV3 need further investigation.…”

Biological Significance of Dual Mutations A494D and E495K of the Genotype III Newcastle Disease Virus Hemagglutinin-Neuraminidase In Vitro and In Vivo

“…Multiple studies have shown that mutations in the HN protein are considered as determinants of in vivo biological activities, such as virulence and pathogenicity [43,44]. We have previously demonstrated that the aa mutations in the HN protein were required for the virulence and pathogenicity of genotype III NDV, but the research content needs to be further enriched.…”

Ecological and Molecular Genetic Characterization of Newcastle Disease Virus

“…Молекулярная основа сайта расщепления белка F (FCS) определяет патогенность штаммов NDV: лентогенный вирус в сайте CS содержит меньше основных аминокис-МЕЖДУНАРОДНЫЙ ЖУРНАЛ ПРИКЛАДНЫХ И ФУНДАМЕНТАЛЬНЫХ ИССЛЕДОВАНИЙ № 10, 2023 13  БИОЛОГИЧЕСКИЕ НАУКИ  лот и лейцин в положении 117 [40], мезогенный и велогенный штаммы имеют многоосновную аминокислоту CS с фенилаланином в положении 117 [41]. Специфическая аминокислотная последовательность белка F тесно связана с тропизмом по отношению к тканям мозга, легких и селезенки [42]. Таким образом, аминокислота в месте расщепления белка F является основным фактором, определяющим вирулентность [43].…”